1. Field of the Invention:
Compensated controls for heat pumps and air conditioning units generally classified in Class 62, subclass 215.
2. Description of the Prior Art:
U.S. Pat. 3,113,439 (Eargle) describes a heat pump system having an outdoor temperature compensated thermostat. A thermistor sensing outdoor ambient air temperature is provided in a circuit which will compensate the control in anticipation of heating and cooling requirements. The variable resistance of the thermistor controls the heat output of a small heater affecting the set point of the thermostat.
U.S. Pat. No. 3,252,295 (Leister Jr.) shows an air conditioning system in which both a low temperature start switch and a low pressure cutout switch cooperate with the power supply to the compressor. If suction pressure is too low, then the low pressure cutout switches off power unless the low temperature start switch is making contact. In this case, an alternate path of power to the compressor is provided.
U.S. Pat. No. 2,218,944 (Wolfert) describes a refrigeration system including a very complex control mechanism utilizing a low pressure bellows connected to the suction side of the system and a high pressure bellows connected to the discharge side of the compressor. These two devices cooperate to prevent startup of the compressor in the event the pressure differential is above some predetermined maximum.
U.S. Pat. No. 3,425,628 (Russell) also describes a system using pressure control lines from the low pressure side of a system to maintain the pressure differential within a predetermined setting. Although similar to Wolfert, described above, this patent is slightly more simplified, but still requires an extraordinary number of levers and actuators to accomplish its function.